Technical Field
The present invention relates to a sheet processing device and an image forming system.
Background Art
There is known a sheet processing device which includes a binding unit provided with an accumulator on which sheets are accumulated, a staple driver for driving a staple from above into a predetermined position of the accumulated sheets, and a staple receiver disposed opposed to the staple driver with the sheets sandwiched between the staple receiver and the staple driver to receive a tip of the staple driven from the staple driver and bend the tip of the staple. The sheet processing device produces a booklet by using the binding unit.
For example, JP 2012-176808 A proposes this type of saddle stitching unit which includes a saddle unit on which creased V-shaped sheets are accumulated in a straddling state over the saddle unit, and a staple driver supported on an arm extended in a direction crossing a ridge direction of the saddle unit at right angles in a horizontal plane. According to this configuration, a staple is driven by upward movement of a staple receiving portion disposed below the saddle unit.
According to the device disclosed in JP 2012-176808 A, the arm extends in a long length direction of the arm. In this case, the rigidity of the staple driver in a short length direction of the arm becomes relatively low. Accordingly, twisting force in the short length direction generated during the staple driving operation may produce mechanical deviation, and cause a shift of a binding position from a predetermined position. Moreover, this twisting force prevents driving of the staple in an appropriate manner, and causes buckling of the staple in some cases.